@article {KNZ001675, title = {Thermal performance of larval longfin dace (Agosia chrysogaster), with implications for climate change}, journal = {Environmental Biology of Fishes}, volume = {98}, year = {2015}, pages = {395 -404}, abstract = {

Temperature is an important factor affecting the distribution of freshwater fishes. The longfin dace (Agosia chrysogaster) is endemic to the Gila River basin of the southwestern USA and northern Mexico and occupies a range of thermal environments from cool mountain tributaries to warm desert rivers but information about its thermal biology is limited, particularly for larvae. We quantified the effect of rearing temperature on survival, growth capacity, and critical thermal maximum (CTM) of larval longfin dace. Broodstocks of longfin dace were collected from two sites in the upper Gila River in New Mexico from which larvae were hatched and reared for 22 days in indoor aquaria at constant temperatures ranging from 18.0 to 31.0 \°C. Growth capacity peaked at 27.0 \°C and was 21 \% greater for larvae hatched from the upstream compared to the downstream broodstock, indicating intraspecific variability in growth capacity. CTM increased with rearing temperature and ranged from 33.9 to 39.9 \°C, indicating that thermal acclimation influences maximum thermal tolerance. CTM and acclimation response ratio of larvae are lower than those of adult longfin dace measured in a previous study, suggesting that larvae are more sensitive and less responsive to thermal stress than adults. Water temperatures in 2012 from six sites in the upper Gila River basin did not exceed 27.0 \°C and larval growth capacities in May of 2012 ranged from 5 to 28 \% of the maximum growth capacity. We assert that rising temperatures may increase larval growth rates, although this will depend on resource limitation and shifts in community interactions.

}, keywords = {LTER-KNZ, Critical thermal maximum, GilaRiver, Growth capacity, Larval fish, Thermal acclimation}, doi = {10.1007/s10641-014-0270-7}, url = {https://link.springer.com/article/10.1007\%2Fs10641-014-0270-7}, author = {Troia, M.J. and Whitney, J.E. and K. B. Gido} } @article {KNZ001674, title = {Alternative spawning strategy and temperature for larval emergence of longfin dace (Agosia chrysogaster) in stream mesocosms}, journal = {The Southwestern Naturalist}, volume = {59}, year = {2014}, pages = {277-280}, abstract = {

To determine if the strategy of spawning in saucer-like depressions is obligate or facultative for longfin dace (Agosia chrysogaster), we collected adults from four sites in the upper Gila River (southwestern New Mexico), stocked them in separate outdoor stream-mesocosms lined with cobble substrate, and made daily observations for the presence of saucer-nests and hatched larvae. Larvae were observed from three of the four mesocosms and emerged at temperatures ranging from 19.2\–24.0\°C. The absence of saucer-nests in all mesocosms throughout the study indicates that longfin dace can spawn over cobble substrate and have larvae hatch successfully, suggesting that longfin dace can use an alternate spawning strategy when sand substrate is not available for construction of saucer-nests.

}, keywords = {LTER-KNZ}, doi = {10.1894/N03-MP-09.1}, url = {http://www.bioone.org/doi/10.1894/N03-MP-09.1}, author = {Troia, M.J. and Whitney, J.E. and K. B. Gido} } @phdthesis {KNZ001654, title = {A mechanistic framework for understanding prairie stream fish distributions}, volume = {PhD. Dissertation}, year = {2014}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS}, abstract = {

A fundamental goal of ecology is to understand environmental associations of species. These associations can provide a basis for predicting spatial distributions in contemporary habitats as well as how those distributions might change in response to anthropogenic environmental change. Developing species distribution models is limited by an incomplete understanding of functional traits, spatial scaling, and the mechanisms and generalities of correlations among abundance and environmental gradients. I address these four issues using observational and experimental approaches. First, I tested opposing mechanisms of community assembly by measuring the dispersion (i.e., diversity) of three types of functional strategies at three spatial scales and along environmental gradients. I found that communities are assembled via abiotic environmental filtering, but the strength of this filtering depends on the spatial scale of investigation, longitudinal network position, and type of functional strategy. Second, I quantified community-environment relationships across thirteen sub-basins, nested within the three major basins within Kansas to evaluate the consistency (i.e., generality) in predictive capability of environmental variables among sub-basins and across spatial extents. I found that longitudinal network position is consistently the strongest predictor of community composition among sub-basins, but in-stream and catchment predictors become stronger correlates of community composition with increasing spatial extent. Third, I used environmental niche models to quantify distributions of four pairs of congeneric cyprinids and found that species within each pair exhibited contrasting stream-size preferences. I then used field experiments to test for differences in individual-level performance between one pair of species (Pimephales notatus and P. vigilax) along a gradient of stream size. I found that adult spawn success and juvenile growth and condition increased with stream size for both species, indicating that these congeners respond similarly to abiotic gradients associated with the river continuum. I concluded that complementary distributions are a consequence of biotic interactions, differential environmental filtering evident in an unmeasured performance metric, or differential environmental filtering by an environmental factor operating at longer timescales. These studies demonstrate the context dependencies of characterizing habitat associations of stream fishes, but also reveal the general importance of stream size and associated environmental gradients in structuring stream fish communities.

}, keywords = {LTER-KNZ, Community ecology, Environmental niche modeling, Fish ecology}, url = {http://hdl.handle.net/2097/17285}, author = {Troia, M.J.} } @article {KNZ001644, title = {Towards a mechanistic understanding of fish species niche divergence along a river continuum}, journal = {Ecosphere}, volume = {5:art41}, year = {2014}, abstract = {

Environmental niche modeling is a valuable tool but it often fails to identify causal links between environmental gradients and individual- or population-level performance that drive species\&$\#$39; distributions. Correlation between the abundances of stream fish species and longitudinal position in stream networks is well documented and is hypothesized to occur through differential environmental filtering of trophic traits. Still, trophically similar congeners often exhibit complementary distributions along stream size gradients, suggesting that other mechanisms are important. We present niche models to test the hypothesis that four congeneric pairs (Teleostei: Cyprinidae) exhibit complementary distributions along a gradient of stream size in the central Great Plains of Kansas, USA. Stream size was the strongest predictor of abundance compared to five other environmental variables tested and three of the four species pairs exhibited complementary distributions along a stream size gradient. We carried out field experiments to quantify potentially causal environmental gradients (food resources, temperature, and turbidity) and four measures of individual performance (adult spawning success and juvenile survival, condition, and growth) along a stream size gradient for one congeneric pair: Pimephales notatus, a tributary species and P. vigilax, a river mainstem species. These experiments revealed an increase in temperature and food resources with stream size, along with a corresponding increase in adult spawning success, juvenile condition, and juvenile growth for both species. We conclude that these congeners respond similarly to abiotic gradients associated with the river continuum and that complementary distributions are a consequence of biotic interactions, differential environmental filtering evident in an unmeasured performance metric, or differential environmental filtering by a direct environmental gradient operating at longer timescales.

}, keywords = {LTER-KNZ}, doi = {10.1890/ES13-00399.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/ES13-00399.1}, author = {Troia, M.J. and K. B. Gido} }